1. Field of the Invention
The invention is concerned with the field of automotive engineering. In particular, the invention relates to safety systems for preventing collisions.
2. Description of the Related Art
Such systems are specifically significant for vehicles which are less easy to steer into critical situations owing to their size, their weight and to a certain extent complex design (for example, a plurality of axles, trailers, containers, etc.).
These vehicles are, for example, trucks (rigid vehicles, semitrailers and trailer vehicles), buses, articulated vehicles and other vehicles (for example recreational trailers), in which the problem arises that existing overhangs in various regions of the vehicle (rear, front, corner edges and superstructures) swing out when turning and maneuvering. In addition, depending on the type of vehicle, a plurality of regions of the vehicle cannot usually be satisfactorily seen from the driver's position so that owing to “dead angles” the driver is frequently unable to monitor swinging out—for example by looking in the mirror—and notice, for example, during a maneuver, when such regions of the vehicle are coming too close to obstacles, and react appropriately. As a result, in tight driving situations there is a risk of colliding with obstacles and other road users, which may result in serious injury to persons and severe damage to property.
Typical situations in which the described problems occur are presented below:
a) Risk of Collisions in the Front Region
In particular, vehicles with a large front overhang (distance between front axle and the front of the vehicle) swing out a very long way when turning or maneuvering and must also move out to a great extent in very narrow streets. As a result, the front of the vehicle moves over a correspondingly large radius, and in particular side regions of the front can quickly impact against obstacles (see FIG. 1). Even when reversing in order to park or performing reversing maneuvers, the front of the vehicle moves in a circular arc shape (locked front wheels) so that there is also the risk of side regions of the front being involved in a collision (see FIG. 2). This risk is increased further as when reversing the main attention of the driver is of course directed at the rear region of the vehicle in accordance with the direction of travel.
b) Risks of Collisions in the Rear Region
In a corresponding way, in the case of vehicles with a large overhang at the rear (distance between the rear axle and rear), there is a risk of collision specifically of the side regions of the rear both when performing maneuvers moving forward and when performing reversing maneuvers (see FIGS. 3 and 4). In particular in the case of vehicles with trailers, semi-trailers or superstructures (for example a vehicle-mounted rotational crane) these risks of collision are particularly pronounced.
c) Risks of Collision with Attached Trailers, Semi-Trailers, etc.
Specific problems arise in vehicles with trailers, semi-trailers or superstructures. In such vehicles, the front of the attached part of the vehicle swings out in the form of an arc when turning or maneuvering in the forward direction and reverse direction so that there is a risk of collision in critical driving situations (see FIGS. 5, 6, 7).
d) Risk of Collision of the Side Regions of a Vehicle
The side regions of a (relatively long) vehicle can also collide with obstacles in a small maneuvering space (see FIGS. 8 and 9).
The situations described show that the problems of preventing collisions as comprehensively as possible are relatively complex. Systems in which distance messages are issued are known. In such systems, the critical regions of a vehicle are monitored by devices (for example ultrasonic sensors, video cameras) which sense when obstacles are approached. When a predefined distance from the obstacle is undershot, the driver is warned, for example, by means of optical or audible signals. However, these systems can detect obstacles and distances in good time only in simple driving situations. For this reason, owing to the vehicle's own movement, warnings are issued too late (or incorrectly) so that as a result of the, under certain circumstances, high chronological dynamics of the driving situation, there is hardly the possibility any more for the driver to react appropriately in good time.
In WO 03/001471 a system is described for avoiding collisions between vehicles and obstacles. Therein the spatial environment of the automobile is surveyed via vehicle sensors and the data derived therefrom is supplied to a data processing unit for computing the area free of obstacles. Other sensors are supplementally used to sense the orientation and position of all moveable vehicle components, as well as dynamic parameters of the instantaneous driving condition. From these data, in the data processing unit the space required for the next time interval of continuation of the vehicle travel is calculated in advance and compared with the actual existing obstacle conditions. This comparison provides an early prediction of a possible collision. In critical situations it is possible, as an aid to the vehicle operator, to make direct input to the vehicle controls via the data processing unit.
U.S. Pat. 5,602,542 A1 describes a system for assisting vehicle operators during the parking process. By using ultrasonic sensors in the vehicle chassis, a distance profile relative to the vehicle body, and of the objects lying closest thereto, is produced. Therein, the contour of the vehicle body is stored in a memory unit. In a similarly organized memory the distancing profile is recorded. In this manner, by the direct comparison of the memory contents with the aid of a microprocessor, the relative distance between the vehicle body and an object in the environment can be continuously determined during parking of the vehicle.